Method of positive printing in color photography



Patented Dec. 30, 1941 METHOD OF POSITIVE PRINTING IN COLOR PHOTOGRAPHY Edwin Bower Hesser and Eva Louise V. Hesser, West Hollywood, Calif., assignors, by mesne assignments, to Photocolor Corporation of America, a corporation of California No Drawing. Application August 24, 1938, Serial No. 226,448

22 Claims.

Our invention relates to new and improved methods of color photography and more particularly to new and improved methods of positive printing in photography and cinematography. A more specific aspect of our invention relates to a new and improved method of printing in color photography from a series of color separation negatives comprising only two units, the first a negative recording blue to blue-green values, and the second a red recording negative.

It is well known in the art to print from two such negatives on opposite sides of double coated positive motion picture film, coloring the positive print from the blue or green negative recording a reddish tone and the positive print from the red recording negative to an iron blue tone, or to other types of coloration producing some variation of colder tones, i. e., from blue to green.

It is also old in the art to produce within a single emulsion positive printings from two cliffering color selection negatives and to differentially color such positive printings with warmer and colder colors of complementary type.

The use of color baths containing a mixture of red and yellow dyes for coloration of the positive printing from the blue or green recording value negatives has been taught, and in the literature is often referred to as coloring of dichroic type, using mixed dyes.

An object of this invention is to provide improved means for the coloration of a positive printing from a blue-green or a green color record negative to the end that substantially correct color rendition of both magenta and yellow be obtained so that when combined with blue,

an excellent three color picture results.

In a preferred form of our invention, the negative employed for positive printing in the warmer colors is as strictly green sensation as the taking of a negative on orthochromatic negative material with a yellow filter will afford. A material proper for this purpose is "Dupac bi-pack, in which the front element, when exposed unfiltered, is blue sensation recording and when filtered with a yellow filter, such as a filter of the K series, becomes green sensation recording, according to the relativity of the filter density employed, the darker or denser filters of the series, such as K2, producing a definitely green recording, while the lighter filtration such as printing of magenta andblue will not produce,

a positive transparency successfully reproducing natural colors, although each of the two color printings are in themselves correct; The fault in such printing lies in the absence of yellow. To

- supply such needed yellow and combine it with magenta and blue is the main object of our invention. We do this by new and novel means which will be described in detail.

In usual practice, a bi-pack is exposed with-- out filtration. The front negative element so produced is thus blue sensation recording, and in tri-color printing would provide a positive print proper for coloration in yellow, but entirely I,

incorrect for printing in magenta or any other shade of red. Defying this actuality, it has been the custom in two-color printing to use this actually blue-recording front element negative, proper for yellow coloration only, as the red printer. In the type of two-color printing striving for dichroic effects, it has been the custom to mix redandyellow dyes in one bath, the theoretical result being a pleasing representation of the warmer colors" of red and yellow.

The actual result of such efforts, however, has been merely a picture composed of an orangereddish coloration from the front bi-pack element, and a blue coloration from the printing in positive form of the rear bi-pack element. As an example, in a picture striving to depict three differently colored balloons, one definitely bright yellow, one red-orange and one magenta, the results of the rendition of each balloon in such two-color printing, as described, would be almost: Both the actually yellow and the ac-,

identical. tually magenta balloons would be reproduced in orange-red and thus be almost identical to the actually orange-red balloon photographed with them.

Among other things, our improvement provides definite differentiation between the photographic reproduction of yellow and magenta and by so doing provides a substantially correct three-color positive print from only two negatives and with only two positive printings, that is, it uses a simple yellow filtered bi-pack for three-color work.

- We expose a bi-pack through a yellow filter of the type described. The front element of the bi-pack when yellow filtered is capable of recording blue-green to green sensations but not red.

atives may be simultaneous or successive.

The rear element is capable of recording substantially red sensations only. A suitable bi-pack comprises a front element having a transparent support, an orthochromatic silver halide emulsion of blue and green, but not red, sensitivity, and a red filter layer removable after development in dilute sodium hydrosulfite. The second element consists of a panchromatic emulsion on a transparent support, optionally containing a non-halation, water-soluble backing layer. It will be understood that the invention is not limited to the use of this particular form of bi-pack. After exposure the latent images in the negatives are developed and fixed in the usual way.

In green sensation recording negatives we discovered the peculiar characteristic of semiopacity in the regions representing yellow, while in the regions representing magenta, complete transparency exists. Thus, in a region representing scarlet red, which contains magenta in combination with yellow, less transparency of the green record negative-exists than in true, deep magenta-red regions. The range of increase in opacity, in the area of a negative representing the warmercolors, is directly relative to the yellow content. Thus, yellow is most opaque, orange slightly less opaque, while the reds, including a heavy percentage of magenta, are substantially transparent. In our method of printing through the green record negative onto a positive light sensitive photographic material, suflicient light is employed to partially penetrate the opacity representing the yellow objects to produce upon the positive a faint silver image, while the almost complete transparency of the darker red-magenta objects photographed is productive of a very pronounced, heavy silver image.

The red sensation negative/and the green recording negative may be printed onto opposite sides of double coated positive stock having a single positive emulsion on each side of a trans parent support. The printing from the two neg- 1- ternatively, the images from both negatives may be formed successively in a single relatively thick positive emulsion layer carried on a transparent support or in two layers on the same side of a single support. If formed in a single emulsion layer, the images are derived from the silver halide originally present. This may be accomplished by printing the image from the red negative, developing without fixing, toning blue, all of said steps being effected while leaving a portion of the emulsion layer unexposed, then print ing from the green negative in the unexposed portion of said layer. Regardless of the type of positive stock used, the intensity of light, duration of printing and density of the green negative during printing and development are so controlled that the more opaque areas of said negative representing yellow are partially penetrated by light and form faint silver images in the positive emulsion for coloring in yellow, while the less opaque areas form heavy silver images for coloring in magenta.

The production of the blue coloration from the rear bi-pack negative may be effected not only by toning but by other means known in the art, whether the silver image so formed is in a separately supported photographic emulsion, whether it occupies a strata in an emulsion which contains an image printed from another negative.

We prefer to apply our coloration for the Warmer colors in the following manner. By known manner, whether the silver image representing these warmer colors is in a single separate emulsion, or it the silver image representing these warmer colors shares a single emulsion with another image representing the cooler colors, the metallic image is converted to an image containing silver iodide by immersion or application of a solution containing iodine, potassium iodide and a mild acid as its principal constituents. It will be understood, however, that any conversion of the silver image representing the warmer colors to a full mordanting medium is usable. Addition of uranium nitrate to the iodine-potassium iodide solution produces a combined mordant and brownish tone which adds a fourth color effect and valuable key print qualities to the finished product.

Following the conversion of the silver image printed from the green separation negative to a mordanting medium, we prefer to apply thereto by mechanical means, such as capillary rollers in a continuous operation, two basic colors in succession which have different capacities of mordanting. The magenta dye solution may be such that it will only mordant in places on the positive where a substantially definite deposit of metallic silver converted to a mordant medium is present. This is effected by using a definitely weak solution of a basic magenta dye such as rhodamine or fuchsine. The yellow dye solution should be of a concentration much stronger than the magenta, capable of mordanting even in areas occupied by very little original silver metallic image, that is, the yellow representing areas of the picture being reproduced in positive form. Successive flotation may be employed instead of capillary rollers. Several rollers in succession may apply one color, for example, the yellow basic dye solution. Following this another series of rollers may apply the magenta solution. We have also alternated the applicator rollers so as to apply yellow on one roller, magenta on the next, then yellow, then magenta, until the series of rollers is complete. We have not found the sequence of application of great importance, but the concentration of basic dye for the magenta coloration must positively be such that greater contrast will be produced than in the yellow dye used, while the yellow, being of difiering concentration, will pick up in the areas not sufficiently dense to mordant an appreciable amount of the contrasting magenta dye. Thus, red lips containing a definite magenta color factor are reproduced in great contrast to the peach colored flesh tones of a face. A magenta balloon, showing very transparently on the green record negative, so completely colors with the contrasting brilliant magenta dye that no appreciable color degradation results from the co-application of the yellow dye solution, which is, in eife'ct, crowded out by the more brilliant magenta.

It is well known in the art that the mixing of two or more dyes in a single solution is a very diflicut and uncertain operation in relation to dye mordanting in photography. Such solutions, due to the differing mordanting propensities and ratio of exhaustion of the constituent dyes, are apt to change color during an operation, providing uncertainty of efiect. We have completely eliminated dye mixing by applying each dye separately. This also has an important effect in allowing us, in the multiple dye solutions used, to control the mordanting contrast not only by the dye content of the separate solutions, but by adding more mild acid, such as acetic, to one dye concentration than to the other. This control enables us to make one dye concentration, such as the yellow, of a flatter nature, and the magenta dye concentration of a more tenacious and contrasting nature.

Concentrations of clearing solutions may be employed to remove surplus dye which have greater eifect upon the yellow dye than upon the magenta. Thus, if a solution containing grams of sodium bi-sulfite in 2000 c. c. of water is employed, in connection with yellow dyeing with auramine and magenta dyeing with fuchsine, the clearer acts much more quickly upon the yellow than upon the magenta. However, if thioflavine is employed for yellow coloration and strong fuchsine for magenta coloration, a similar clearing bath acts much more quickly upon the magenta than upon the yellow. Thus, a very heavy magenta coloration with fuchsine may completely occupy the more dense areas of the positive and to a lesser extent the lighter areas, in conjunction with the separately applied thioflavine basic yellow. A clearing concentration removing the'magenta color from the weaker densities may be employed, so that the magenta remains strong and contrasting in the denser areas, with all scales of photographic gradation, while the thioflavine remains in the lighter density areas, carrying out the spirit of the invention. Thus, a yellow ba loon producing low density area on positive print would retain its yellow, a magenta balloon producing greater density would retain its magenta coloration, and other objects representing gradations of warmer colors between yellow and magenta would be represented by appropriate color gradations sub stantially reproducing the variations in the warmer section of the spectrum.

While we have sometimes employed alternate rollers of capillary type to apply the differing unmixed basic dyes, we have found that this method necessitates partial drying, such as by air squeegee, between the dye applicating contacts, in order to avoid the mixing of the dyes.

We have utilized another and simpler control method, based on our discovery that when a mordanting material is fresh, that is, in a period immediately following, the conversion of a silver metallic image to an image capable of mordanting basic dyes, even the weakest silver image will strongly pick up or mordant the content of a dye solution of proper concentration. The same medium, after a few minutes of plain water washing, is much less able to pick up dye from a solution, because some of the mordanting medium, in the form of silveriodide salts, for instance, is washed away. We have utilized this discovery by first app ying a yellow basic dye solution to the freshly bleached silver images, i. e., silver images treated with a bleaching solution, cleared of iodine stain and rinsed momentarily, avoiding any prolonged washing. The yellow thus applied picks up in every part of the mordanting image, in a "flat or noncontrasting manner, but with a degree of tenaciousness necessary to remain in the colloid emulsion through the succeeding operations. Following the application of the yellow dye, the film is washed and preferably dried partially with air squeegee, the washing operation being such that some of the mordanting medium is washed from the film, particularly from the regions where the silver image was slight, as in the yellow-representing areas. However, where a heavy original silver image was present, as

in the magenta representing areas, and those while the yellow coloration, first applied, would remain flat but, nevertheless, supplying in the proper areas the color necessary to create a three-color picture from the printing of only two negatives.

Thus, the propensity of a mordant medium to partially wash away has provided us with means to produce a flat yellow image in association with a magenta image of much greater contrast, a method of color control which we believe to be both unique and valuable in commerce.

In our extended experiments which led to the discovery of these methods of color control we also employed an alternate method, carrying out the principles of our invention, as follows:

Silver images are printed in the usual manner from the green and red sensation recording negatives by means of exposure, development and fixation. The images formed from the red sensation negative are toned blue, the silver images from the green sensation recording negative being at this state of the process unchanged. Normally, the next step would be to convert this positive image from the green sensation recording negative to a mordant medium by the bleaching method. In our present alternation of processing, instead of bleaching, we apply to the unchanged silver image a suitable concentration of yellow basic dye resulting in an impregnation of the entire emulsion containing the image, the colloidal gelatine base absorbing the dye to a point of saturation but in a transient manner, inasmuch as simple water washing would be suflicient to eliminate the dye for which neither the silver image or the colloid comprising the emulsion has any permanent affinity. However, for the time being the emulsion is filled with yellow dye, and when, in our next step, we apply to the same emulsion and its contained silver image a conversional solution capable of changing the silver image to a mor danting image, the result is the immediate mordanting of the yellow basic dye to the mordanting image. The dye used in this instance is so strong that the subsequent operation of clearing with a bisulfite to remove the iodine stain will not remove the yellow coloration but will leave it definitely flat or non-contrasting in character. Short washing will now eliminate the mordanting qualities of the thinner parts of the picture representing mainly the yellow areas. The magenta basic dye solution is next applied, resulting in a properly contrasting magenta part-picture which correctly represents the positive from the green sensation recording negative, according to the contrast degree desirable for magenta coloration.

We discovered that while complex in its handling, and requiring special machinery, this method of applying one color to an unbleached" or normal metallic silver image, then applying the mordant medium, followed by the application of another color, has many advantages in clarity of result and uniformity of coloring. It admirably provides the separation of treatment and the absence of dye mixing which results in proper variation between the desired flat yellow" and "contrast magenta colorations which when com- I bined with the blue part-image obtained from the red sensation negative provides a meritorious three-color picture.

We do not intend to limit the scope of our invention to front bi-pack negatives of orthochromatic type produced by the usage of a yellow filter during photographic exposure. We have obtained equally excellent results with green record negatives obtained on panchromatic material, green filtered in exposure. Among the combination of unmixed dyes which we may employ in order to produce yellow and magenta positive colors in an image formed from a green to blue-green negative are the following:

Thiofiavine and fuchsine Thioflavine and rhodamine Auramine and fuchsine Auramine and rhodamine As a typical example of the relative concentrations if auramine is used in conjunction .with rhodamine, the following concentrations may be employed:

(1) Auramine grams 20 Water ..c. c 2000 (2) Rhodamine grams Water c. c 2000 A typical mordanting composition which can be applied to the positive stock prior to the application of the dyes may be as follows:

Iodine grams 6 Potassium iodide 'd0 50 Water c. c 1000 Glacial acetic acid c. c 10 Another type of mordanting composition which has been found to be especially satisfactory is the following:

Uranium nitrate -r grams 12 Oxalic acid do a 6 Potassium ferricyanide do 8 Iodine resublimed do 6 Potassium iodide do.. 50 Acetic acid glacial c. c 50 Water to c. c. 4000 It will be understood that other types of mordanting agents may be employed.

We include within the scope of our invention all successive applications of dyes by mechanical or flotational means in which the differing, independent dye solutions act upon the same images formed from silver metal converted to a mordanting medium and in which the concentrations of dye, or of dye with mild added acid or dye controlling mediums, is such that the multiple dye solutions employed have differing qualities of contrast in mordanting operations and/or differing qualities of washing out or expulsion from the image under the influence of clearing solutions so applied as to reach both colors. We believe that the successive application of two radically differing dye solutions, differing in color and/or contrast controlled by dye content and/or contrast controlled by acetic acid content in conjunction with dyes, is radically different in effect from any single solution containing red and yellow and which acts on a single silver image converted to a mordant.

The expression negative recording essentially green sensations is employed herein, to describe generically negatives such as may be obtained by exposing an object to panchromatic stock through a green filter, or by exposing an object through a yellow filter to a photographic emulsion capable of recording blue and green sensations but not red sensations.

Having thus described the invention, what we claim as new and desire to secure by Letters Patent of the United States is:

l. A process in color photography which includes the following steps: forming a latent, positive silver image in a photographic emulsion by the action of light penetrating an orthochromatic negative priorly yellow filtered in the taking operation; developing, fixing and washing the latent image; impregnating with a solution containing iodine, potassium iodide and uranium nitrate, thus forming a brownish key image and rendering the silver image receptive to basic dye mordanting; impregnating with a solution containing a basic yellow dye; washing to sumciently remove mordanting ability from the fainter portions of the image without destroying the dye receptivity in the heavier portions thereof; impregnating with a solution containing a basic magenta dye to mordant into the heavier image portions; washing to clear the highlights; thus producing an image in brown, yellow and magenta.

2. A process in color photography which includes the following steps; printing a positive silver image from a yellow filtered orthochromatic negative; developing and fixing such image upon its associated flexible transparent support; impregnating with a yellow basic dye in solution; applying thereto a combination toning and mordanting solution containing iodine, potassium iodide and uranium nitrate; washing sufficiently to remove the dye receptivity from the fainter portions of the image; applying a magenta dye solution to mordant into the heavier portions of the image remaining dye receptive; and washing to clear the highlights.

3. A process in color photography which includes the following steps; forming a latent positive silver image in a photographic emulsion by the action of light penetrating a developed and fixed blue-green sensitivity orthochromatic negative; developing, fixing and washing the latent image; impregnating with an aqueous solutional bath containing uranium nitrate, potassium iodide, and iodine; impregnating with an aqueous solution containing a yellow basic dye, thus forming a brownish'key image yellow mordanted and rendered receptive to further basic dye mordanting; washing to sufficiently remove mordanting ability from the fainter portions of the image without destroying the dye receptivity in the heavier portions thereof; impregnating with a solution containing a basic magenta dye to mordant into the heavier image portions; washing to clear the highlights; thus producing an image in brown, yellow and magenta.

4. A process in color photography which includes the following steps; forming a latent positive silver image in a photographic emulsion by the action of light penetrating an essentially green sensation recording negative; developing, fixing and washing the latent image; impregnating with a solution containing iodine and potassium iodide, thus rendering the silver image receptive to basic dye mordanting; impregnating with a solution containing a basic yellow dye; washing to sufficiently remove mordanting ability from the fainter portions of the image without destroying the dye receptivity in the heavier portions thereof; impregnating with a solution containing a basic magenta dye to mordant into the tion containing a basic yellow dye; washing to sufficiently remove mordanting ability from the fainter portions of the image without destroying the dye receptivity in the heavier portions thereof; impregnating with a solution containing a basic magenta dye to mordant into the heavier image portions; washing to clear the highlights; thus producing an image in brown, yellow and magenta.

6. A process in color photography which includes the following steps: forming a latent positive silver image in the light sensitive residue of a photographic emulsion already bearing a blue toned image by the action of light penetrating a green sensation recording negative; developing, fixing and washing the latent image; impregnating with a solution containing iodine, potassium iodide and uranium nitrate, thus forming a brownish key-image and rendering the silver image receptive to basic dye-mordanting; impregnating with a solution containing a basic yellow dye; washing sufficiently to remove mordanting ability from the fainter portions of the image without destroying the dye receptivity in the heavier portions thereof; impregnating with a solution containing a basic magenta dye to mordant into the heavier image portions; washing to clear the highlights, thus producing an image in brown, yellow and magenta.

'7. A process in color photography which includes the following steps; printing a positive silver image from a yellow filtered orthochromatic negative in the remaining light sensitive material of an unfixed photographic emulsion already bearing a chemically blue toned image; developing and fixing such image upon its associated flexible support; impregnating with a basic yellow dye in a solution; applying thereto a combination toning and mordanting solution containing iodine, potassium iodide and uranium nitrate;

washing sufiiciently to remove the dye receptivity from the fainter portions of the image; applying a magenta dye solution to mordant into the heavier portions of the image remaining dye receptive; washing to clear the highlights.

8. A process in color photography which includes the following steps; forming a latent positive silver image in a light sensitive photographic emulsion by the action of light penetrating a yellow filtered orthochromatic negative; developing, fixing and washing the latent image; impregnating with a solution containing iodine, potassium iodide and uranium nitrate, thus forming a brownish key image and rendering the silver image receptive to basic dye mordanting.

9. A process in color photography which includes the following steps: printing a positive silver image from a substantially green sensation recording negative; developing and fixing such image upon its associated flexible transparent support; impregnating with a yellow basic dye in solution; applying thereto a combination toning and mordanting solution containing iodine, potassium iodide and uranium nitrate, thus iorming a brownish key image and mordanting the yellow basic dye thereto,

10. A process in color photography which includes the following steps; forminga latent positive silver image in the remaining unfixed light sensitive area of a photographic emulsion already bearing a chemically toned image by the action of light penetrating a green sensation recording negative; developing, fixing and washing the image upon its associated supporting material; impregnating with a solution containing iodine, potassium iodide and uranium nitrate, thus forming a brownish key-image and rendering the silver image receptive to basic dye mordanting.

11. A process in color photography which includes the following step; impregnating a positive silver image with a solution containing iodine, potassium iodide and uranium nitrate, thus forming a brownish key image and rendering the silver image receptive to basic dye mordanting.

12. A process in color photography which includes the following steps: forming a latent positive silver image in the remaining unfixed light sensitive area of a photographic emulsi already bearing a chemically toned blue' i age by the action of light penetrating an exposed, developed, fixed and dried photographic negative recording blue to green/ color sensations but not recording red color sensations; developing, fixing and washing the image upon its associated supporting material; applying thereto an aqueous solution containing iodine and potassium iodide, thus rendering the silver image receptive to basic dye mordanting; impregnating with a solution containing a yellow basic dye; washing to remove excess yellow coloration and to remove mordanting ability from the fainter portions of the image without destroying the further dye receptivity in the heavier portions thereof.

13. A process in color photography which includes the following steps: forming a latent positive silver image in the remaining unfixed light sensitive area of a photographic emulsion already bearing a chemically blue toned image by the action of light penetrating an orthochromatic blue sensation recording negative; developing, fixing and washing the image upon its associated supporting material; impregnating with a solution containing iodine, potassium iodide and a mild acid; impregnating with a solution containing a yellow basic dye; washing to remove excess yellow coloration and to destroy further mordanting receptivity in the fainter portions of the image.

14. A process in color photography which includes the following steps; forming a latent positive silver image in the remaining unfixed light sensitive area of a photographic emulsion already containing a chemically toned image by the action of light penetrating multiple exposed, developed, fixed and dried photographic color recording emulsions, one of which is a negative recording the blue to green region of the spectrum; developing, fixing and washing the image upon its associated supporting material; impregnating with a solution containing iodine, potassium iodide and uranium nitrate, thus forming a brownish key image and rendering the silver image receptive to further dye mordanting.

15. A process in color photography which includes the following steps; forming a latent positive silver image in a photographic emulsion by means of light penetrating a color sensation recording photographic emulsion which has been developed, fixed, washed and dried following exposure; developing the latent positive silver image; washing and impregnating with a solution containing iodine, potassium iodide and uranium nitrate, thus forming a brownish key-image and rendering the silver emulsion receptive to basic dye mordanting.

16. A process in color photography which in- .cludes the following steps: exposing a photo graphic negative material with such filtration as to effect substantial green sensation recording in combination with practical opacity in the regions recording yellow objects; developing, fixing, washing and drying the negative thus formed; utilizing this negative for the penetration of light to form a latent positive silver image in a photographic emulsion; developing, fixing and washing the image so formed; while still wet impregnating with an aqueous solution containing iodine, potassium iodide and uranium nitrate; impregnating with a solution containing a yellow basic dye; washing to remove surplus yellow dye and reduce the sensitivity of mordanting ability in the fainter portions of the image; impregnating with a magenta basic dye, washing to clear the highlights, thus producing yellow coloration in the regions corresponding to yellow objects in the object photographed; magenta coloration corresponding to green sensation recording areas and a brownish key image.

17. A process in color photography which includes the following steps; providing a positive emulsion in which a positive cyan-blue toned image is situated adjacent to the transparent support underlying emulsion rendered reconversionally light sensitive; providing a color sensation negative recording other than red sensitivities; providing ordinary developing and fixing solutions known in photography; providing a. mordanting solution including iodine, potassium iodide and uranium nitrate; exposing the said positive film to light interrupted by said negative thus forming a latent image in the remaining unfixed area of the photographic emulsion already bearing another image; developing, fixing and washing said image; impregnating with said mordanting solution, thus forming a brownish key image and rendering the silver image receptive to basic dye mordanting.

18. A method of color photography which comprises photographing an object on dual emulsion photographic negative with beam splitting device to record multiple difiering color sensations on the same film; developing and fixing said negative film to obtain differing multiple color sensation negative recordings; printing from the red sensation recording areas thereof a positive form of said red recording; printing from said positive red recording onto the outer plane surface of a motion picture film coated upon only one side with a positive emulsion to form a latent image; reversally developing by known photographic means to form a positive silver image representing said red original recording adjacent the support on said positive film; toning said positive image cyan-blue, reconverting said surface emulsion to further light sensitivity by known photographic procedure, forming in said sensitive emulsion a latent image by the action of light penetrating an area of original negative recording other than a red record sensation; developing and fixing said image; impregnating with a mordanting solution containing uranium nitrate, iodine and potassium iodide in the presence of potassium ferricyanide and acids to form a brownish key image and render the said silver image receptive to dye mordanting.

19. A process in color photography which includes the following steps; providing commercial motion picture bl-pack negative stock unexposed; providing commercial double-coated motion picture positive stock; providing solutions for developing and fixing operations providing a mordanting solution containing uranium nitrate, iodine and potassium iodide; exposing said bipack to an object to form latent images; developing, fixing, washing and drying said latent images, thus forming color separation negatives of differing selective sensitivities; printing said negatives onto opposite sides of said positive stock to form latent images; developing and washing said latent images on their supports; impregnating with said mordanting solution to form a brownish image and render the emulsion capable of basic dye mordanting."

20. A process in color photography which includes the following steps; providing motion picture multiple emulsion light sensitive color selective film unexposed; providing commercial single coated positive film stock unexposed; providing known photographic solutions for development, reversal and fixing operations; providing a mordanting solution containing uranium nitrate, iodine, potassium iodide and potassium ferricyanide in the presence of acetic acid; providing a camera to expose said color selective film; exposing said selective film to an object and developing to form proper color recordings; expos ing from a red record positive to the outer plane surface of said positive film to form a latent image; developing said film reversally to form a positive silver image in the residue unexposed underlying said latent image; toning said residual emulsion cyan blue thus forming positive image adjacent to the transparent support; reconverting surface vacant emulsion to sensitivity by known means; exposing from a green blue record again to the outer plane surface of said positive film to form a latent image; developing and fixing said film; impregnating with said mordanting solution to form a brownish image and render film receptive to basic dye mordanting.

21. A method of color photography which comprises photographin an object on photographic negative material to record multiple differing color sensations; developing and fixing said negative material to obtain differing multiple color sensation negative recordings; printing from the red sensation recording areas thereof a positive form of said red recording; printing from said positive red recording onto the outer plane surface of a positive motive picture emulsion to form a latent image; reversally developing by known photographic means to form a positive silver image representing said red original recording jacent the support on said positive film; toning said positive image cyan-blue; reconverting said surface emulsion to further light sensitivity by known photographic procedure; forming in said sensitive emulsion a latent image by the action of light penetrating an area of original negative recording other than the red sensation; developing and fixing said image; impregnating with a mordanting solution containing uranium nitrate, iodine and potassium iodide in the presence of potassium ferricyanide and acids to form a brownish key image and render the said silver image receptive to dye mordanting. I

22. A process in color photography which ineludes the following steps; providing motion picture negative stock unexposed; providing .commercial motion picture positive stock; providing solutions for developing and fixing operations; providing a mordanting solution containing uranium nitrate, iodine and potassium iodide; providing a cyan-blue toning solution; exposing said negative stock to an object to form latent images of differing multiple selective sensitivities; developing, fixing, washing and drying said latent images thus forming color separation negatives;

printing said negatives onto said positive stock to form latent images; developing and washing said latent image-bearing emulsions on their supports; impregnating an emulsion with said cyanblue solution to form blue positive image; pregnating with said mordanting solution to form a brownish image and render the emulsion capable of basic dye mordanting.

EDWIN BOWER HESSER. EVA LOUISE V. HESSER. 

